Preparation of polyacetals/cyclic acetals from polyketone

Abstract

A process for preparing polyacetals having less than 10% by weight carbonyl containing units and in which the molar ratio of acetal to furan units is greater than or equal to 15:1 is provided. The process comprises reacting a linear alternating polymer of carbon monoxide with one or more olefins (polyketone) with a diol at elevated temperature in the presence of an acid e.g. para-toluenesulphonic acid while continuously removing water generated by the reaction. Water is preferably removed by azeotropic distillation using a water-immiscible solvent.

I claim: 
     
       1. A process for preparing a polyacetal comprised of one or more acetal unit of formula: ##STR4## wherein Z is a divalent group having the formula --(C(R) 2 ) n  -- where the R groups are independently H, OH, C 1  to C 10  alkyl or C 1  to C 10  hydroxyalkyl and n is 2 to 6 and containing less than 10% by weight of groups of formula: ##STR5## wherein the R 1  groups as being independently hydrogen C 1  to C 10  alkyl, or phenyl with the proviso that the molar ratio of total acetal units of formula (I) to furan groups of formula: ##STR6## is greater than or equal to 15:1, which process comprises the steps of: (a) reacting a linear alternating polymer of carbon monoxide and one or more olefins with a diol at elevated temperature in the presence of an acid catalyst, and (b) continuously removing from the reaction medium water generated by the reaction occurring in step (a).   
     
     
       2. A process as claimed in claim 1 wherein the molar ratio of linear alternating polymer to diol in step (a) is in the range 1:2 to 1:50. 
     
     
       3. A process as claimed in claim 2 wherein the molar ratio of linear alternating polymer to diol in step (a) is in the range 1:10 to 1:40. 
     
     
       4. A process as claimed in claim 1 wherein step (a) is effected in a solvent which is immiscible with water and forms an azeotrope therewith. 
     
     
       5. A process as claimed in claim 4 wherein the solvent is selected from benzene, toluene or xylene. 
     
     
       6. A process as claimed in claim 5 wherein in step (b) water is continuously removed by azeotropic distillation. 
     
     
       7. A process as claimed in claim 1 wherein the linear alternating polymer is either a copolymer of ethylene and carbon monoxide or a terpolymer of ethylene, carbon monoxide and an alpha-olefin selected from the group consisting of propylene, but-1-ene, hex-1-ene and styrene. 
     
     
       8. A process as claimed in claim 1 wherein the diol is a vicinal diol selected from 1,2-propylene glycol, 1,2-butylene glycol and 1,2-pentylene glycol. 
     
     
       9. A process as claimed in claim 1 further comprising the step of isolation and purifying the polyacetal from the product of step (b).